This invention relates generally to knife fixtures and related knife blades for use in cutting food products, particularly such as cutting potatoes into elongated French fry strips and the like. More specifically, this invention relates to an improved knife fixture of the type including a plurality or grid of knife blades for cutting food products, wherein the knife fixture includes means for monitoring the knife blades to provide a prompt indication of a broken blade.
Knife fixtures for use in cutting food products into elongated strips are well known in the art, particularly in the potato industry for cutting potatoes into French fries. In one common form, such knife fixtures include a plurality or grid of knife blades mounted along a tubular pathway through which potatoes are propelled in rapid succession one at a time by a water flow stream or the like for passage into cutting engagement with the knife blades. The potatoes are propelled with a sufficient force to drive the potatoes through the knife fixture, whereby the each potato is cut into a plurality of elongated strips. In one fixture configuration, relatively sturdy knife blades are assembled in a complex tree-like arrangement defining a grid of cutting edges which intersect at right angles for cutting each potato into strips. See, for example, U.S. Pat. Nos. 3,109,468 and Re. 32,822. In another and considerably simplified form, a pair of knife fixtures are provided, each including a plurality of relatively lightweight knife blades arranged with cutting edges in parallel relation; the pair of knife fixtures are installed in close series succession along the passage, with the sets of blades of the two fixtures oriented generally perpendicular to each other for cutting each potato into strips. See, for example, U.S. Pat. No. 5,343,623. The latter knife fixture construction beneficially provides a simplified and economical blade shape which can be supported under tension to provide improved food product cutting without requiring a highly sharpened cutting edge.
Knife fixtures of the general type described above are widely used in the potato processing and other foods processing industries, for cutting large quantities of food products in a relatively short period of time. However, the knife blades are susceptible to breakage or damage to the cutting edges, especially in the event that a foreign object such as a rock is propelled along the production passage into contact with the knife blades. Alternately, a foreign object such as a rock can become lodged or stuck in the production passage at the knife fixture. The occasional presence of a rock or the like in the production passage is difficult to prevent in the potato processing industry wherein potatoes are processed at a high production rate and many rocks visually appear similar to a small potato.
When one of these problems occurs, subsequent potatoes may fail to pass through the knife fixture resulting in substantially immediate obstruction of the production passage. In the past, the production passage typically encounters substantial plugging before the existence of the broken blade can be identified and the production line shut down for remedial action. Significant time has been required to unplug the production passage, in addition to repairing the knife fixture, before normal production can be resumed. Alternatively, in the event that the broken blade does not result in obstruction of the production passage, the knife fixture will typically produce poorly cut or improperly cut products of marginal or unacceptable cut quality. A significant quantity of unacceptable product can be produced in a short period of time, unless the product cut quality is regularly and closely monitored for prompt identification of a broken knife fixture blade.
The present invention relates to a modified knife fixture having a plurality of knife blades for cutting food products such as potatoes into strips, wherein the knife fixture includes a detector system and method for substantially immediately identifying a broken knife blade so that the production line can be halted substantially immediately without significant obstruction, and without significant production of unacceptable products, thereby permitting rapid replacement or repair of the knife fixture and a corresponding rapid resumption of normal operation.